WordPress 3 Plugin Development Essentials [Paperback]

There were two things about this book that I really liked: First, it didn't start with just writing a useless "Hello, World" program. Instead, it begins by guiding you through *breaking* an existing plugin, illustrating the sorts of errors you might come across on your own, and how to fix the problems when they occur. Then they move on to modifying the plugin to show how some simple changes affect how it works. Second, they don't spend the whole book building up one monolithic project like a shopping cart or product catalog site. Instead, each of the main chapters builds an individual plugin, with distinct functionality. Each plugin helps illustrate several concepts important to being able to build your own plugins.

On the down side, there were a couple of places where the authors missed out on using some best practices. In building their Ajax Search plugin, they did not use the existing WordPress Ajax APIs, which make a plugin more adaptable to various site configurations. Instead, they use a more fragile method of using a separate server-side component which has to hard-code the path to the wp-loader file. This is a pretty common mistake, but definitely one to avoid. Also, when illustrating how to build settings pages for plugins, they build the form HTML by hand, rather than using the Settings API. By using the Settings API, they would help future-proof the code against future stylistic changes in the admin interface, and would also automatically get handling option data validation and saving options to the database. Hopefully there will be later editions in which they can improve these minor shortcomings.

Overall, I'd say this is quite a good book for both beginners and advanced developers wishing to learn how to build plugins for WordPress (keeping in mind the two caveats I mentioned). They begin with simple examples of how to fetch and use post information and explanations of WordPress 'action' and 'filter' hooks, and move on to more advanced topics such as the WP_Widget class, creating option pages, creating custom post types, and using the shortcode API.

It's without a doubt that WordPress is one of the largest content management systems out there. WordPress has been known for its easy to use software and along with its extendability.

WordPress's extendability features, called plugins, have always been loved by WordPress's users as they provide an elegant system to expand WordPress to do practically anything.

With Packt Publishing's latest WordPress book, WordPress 3 Plugin Development Essentials, it provides a nice and fairly detailed (281 pages) description on how WordPress 3 handles plugins.

What I really love about WordPress 3 Plugin Development Essentials is that it starts off the first few chapters very simply. When just reading the first chapter, it explains on how setting up your WordPress development system, best coding practices (which can be used for no matter what you're programming), and how handle testing, code versioning, security, along with other things. For anyone reading this book, they most likely already have programming experience, and because the authors decided to start this book out in a way that's not too in a rush, it really means quite a bit. It's a great way to start off a book entirely on development...

Just like the first chapter, the second chapter doesn't rush you at all; in fact, it's more of giving you baby steps to start building powerful WordPress plugins. Any kind of developing book can be boring with all that computer code. But the best part I love about WordPress 3 Plugin Development Essentials is that you're not going to be seeing pages and pages of code; the authors give you some code, and describing what it's accomplishing. I've seen books that have two or three pages, back to back, that's filled with code only. No reader is going to give that code a good glance, it'll just confuse them. So with WordPress 3 Plugin Development Essentials, it takes a completely different approach; it takes the main functions of a plugin, the anatomy of a plugin, and breaks it down in an easy to comprehend way.

In the second chapter, there's one thing that rather surprised me in a WordPress plugin development book. In just the second chapter, the author has you making a plugin, that is, an "evil functionless plugin". The author includes some errors in the plugin, where to put the header() function, whether or not to close the PHP tags (this was my favorite part of the chapter. Some WordPress users may edit a plugin, put some whitespace at the bottom, and find that everything is not working right. I'm glad this was added.), and a brief explanation to hooks.

With WordPress 3 Plugin Development Essentials brief introduction to hooks, the authors did one amazing job describing how they work in a simple manner. Hooks are extremely important in WordPress plugin development, if you didn't have it, your plugin wouldn't be as effective.

The next section of WordPress 3 Plugin Development Essentials is where everything starts coming together. The book guides you though implementing a Digg social media button next to each post. An easy concept, but ideal for learning how WordPress handles its plugins. The steps taken in this chapter to implement this feature is so nicely laid out, that you can practically use it as a guide when writing your own plugin. The authors don't rush into things, they make sure what you're going to implement will work, layout the general plan, create the main system, test it, add some more, and test it again. This approach was something that I really appreciated. As a programmer myself knowing many languages (really, don't get me started), I can truly say you want to take programming step by step.

The next two chapters are very similar to the previous one. You learn how to create a content rotator in the widget (typically a sidebar) section, which is very popular among WordPress blogs, and using the power of custom fields to expand the attached content to a post. With the content rotator, they could have integrated some neat jQuery content rotator, but I'm sure the reader can figure that out after reading the chapter. This is actually a very crucial chapter though, you learn how to integrate a widget with custom settings into WordPress! After that, you'r going right to the custom fields. Custom fields in WordPress is simply a way to put more content into your posts and do something with it. Personally, I use custom fields quite a bit on Tech Cores to get many of the things done that WordPress can't do out of the box.

What's fairly ironic is the how WordPress 3 Plugin Development Essentials described on how to implement custom fields is nearly identical to the way on how I accomplished it. Anyways, when getting back to the topic, I was very thrilled to read over this section. If there's one thing you should pick up from this book, it would have to be custom fields. With this small little feature, you can expand WordPress to do practically anything you want it to do. And yes, by the way, the way the authors described this is one of the best ways that I've ever heard. I have to give them an A+ on this entire chapter.

The next section is all about shortcodes. These are simply just like BBCode, but act as powerful extension to the text editor in WordPress. This was a fairly simple chapter, but using the function, register_post_ type(), the authors were left with very little documentation about it; they ended up writing a chapter that I think, should be available on the WordPress Codex. I'm glad that WordPress 3 Plugin Development Essentials decided to make it so it was easy to understand in a practical use. Also, there's one thing that really let me down in this chapter. Like with many plugins, I see the plugins shortcode integrate with the TinyMCE text editor in WordPress to provide a GUI to shortcodes. I really think the authors should have added something like this as an example.

WordPress 3 Plugin Development Essentials explains how to version your code using Subversion. Even though I prefer to use Cornerstone, the book explains how to do it the command line way, which will work on any operating system. This is a great chapter, it even discusses Google Code, but it seems a little out of place. I'm glad they added it, but I personally don't think they needed a full chapter on it.

The next chapter, is a very crucial part of WordPress plugin development: getting your plugin ready for the world! The authors review some common mistakes that make the plugins glitchy on other systems, like conflicting names. This entire chapter is all based upon testing, discussing WordPress limitations, and more. This chapter really tells you the things you need to make sure of when turning a development plugin into a released one.

You guessed it, the next chapter is releasing your plugin for real! This discusses some more best practices and things like localization, getting your plugin noticed, along with some minor things. Great chapter with lots of information!

The last good amount of pages include the appendix which just provides extra reference material (the WordPress Codex is amazing!). Just many of Packt's books, you can easily use this book as a reference guide when you need to. It only covers the essentials of WordPress plugin development, but enough for you to get practically anything done.

Overall, I really enjoyed WordPress 3 Plugin Development Essentials. It was a great short read and I learned a few extra tricks along the way. If you are a causal WordPress developer or you want to be, I highly recommend for you to pick up a copy.

It has been a while since I last developed a plugin for WordPress. With the release of version 3, I have been eager to learn about new improvements with plugin development. Having recently got hold of a copy of WordPress 3 Plugin Development Essentials, I've shaken the dust off my WordPress skills!

Whether you are a newcomer to WordPress, as long as you have some basic PHP knowledge, WordPress 3 Plugin Development Essentials provides a good solid foundation for how to develop your own plugins for WordPress. The book provides practical hands-on tutorials, best coding guidelines and good architecture advice for developing original plugins.

The first two chapters are aimed to ease you into preparing for WordPress, understanding the framework, setting up a development environment and an anatomy of a plugin. Next few chapters are examples of specific plugin functionality. With the remaining several chapters focusing on the deployment, distribution and maintenance of your plugins.

If you are looking to get into plugin development, I'd recommend picking up a copy of WordPress 3 Plugin Development Essentials - while it is not intended to teach you PHP or MySQL, there focus is more on the core concepts, so even regular users of WordPress can delve into making their own basic plugins.

In particular I was impressed with the level of detail on how to use Subversion (Chapter 8), especially with how to overcome various errors and reverting to previous versions. The chapter on 'Standardized Custom Content' is a great resource if you are interested in pushing the boundaries of WordPress towards being a custom content management system.

Having had a fair amount of experience with developing WordPress plugin in the past, I was already familiar with most of the concepts - this book helped to reinforce those principles. If you are interested in learning more how to develop your own WordPress plugins, I would recommend that you pick up a copy of this book.